The invention is related to medical and veterinary technology and procedures. More specifically, it concerns a convenient method for preparation of a fibrinogen adhesive directly from withdrawn blood.
The need for a suitable tissue adhesive for use in surgical procedures in human and animal medicine is well understood, and has been for nearly a century. Various substances have been tried, including completely synthetic materials such as cyanoacrylate. Because, however, the ability of the natural material fibrin to behave as an adhesive is known, fibrin powders were used for this purpose early in the development of this technology.
It has also long been recognized that the in situ formation of fibrin from fibrinogen is a preferable approach. In a relatively recent article, Staindl, O., in Ann Otol (1979) 88:413-418, described the use of a combination of three separately prepared substances, human fibrinogen cryoprecipitate, thrombin in the presence of calcium ion, and Factor XIII concentrate, to obtain a glue that was applied in skin graft applications, myringoplasty, repair of dural defects, hemeostatis after tonsillectomy, and tracheoplasty. Around this time, Immuno-AG, Vienna, Austria, began producing and commercializing a two-component xe2x80x9cfibrin sealxe2x80x9d system, wherein one component contains highly concentrated human fibrinogen, Factor XIII, and other human plasma proteins, prepared from pooled blood, and the other component supplies thrombin and calcium ion. The two components are added together in the presence of a fibrinolysis inhibitor. After application, the processes of coagulation and fibrin cross-linking occur. Eventually, the seal may lyse in the process of healing of the wound or trauma which accompanies the reconstruction of the tissue. Redl, H., et al., xe2x80x9cBiomaterials 1980,xe2x80x9d Winter G. D., et al., eds. (1982), John Wiley and Sons, Ltd., at pages 669-675, describe the development of an applicator device for this system which mixes and applies the two components of the system simultaneously.
This two-component system has been marketed over the last ten years under the trade name Tissucol(copyright) or Tisseel(copyright), and a number of publications have appeared describing the use of this preparation in surgical procedures. See, for example, Seelich, T., J Head and Neck Pathol (1982) 3:65-69; O""Connor, A. F., et al., Otolaryngol Head Neck Surg (1982) 90:347-348; Marquet, J., J Head and Neck Pathol (1982) 3:71-72; Thorson, G. K., et al., J Surg Oncol (1983) 24:221-223. McCarthy, P. M., et al., Mayo Clin Pros (1987) 62:317-319, reported the addition of barium ion to this fibrin glue system in the treatment of a bleeding duodenal sinus in order to facilitate follow-up surveillance. See also Portman, M., J Head and Neck Pathol (1982) 3:96; Panis, R., ibid., 94-95.
It has been recognized, of course, that the use of the commercial product, which is prepared from pooled human blood, poses at least a theoretical risk of contamination by disease-producing organisms, especially viruses. The earlier concerns were directed to transmission of hepatitis B, but more recently the focus has shifted to concern about inadvertent transfer of the AIDS virus. Therefore, attention has been given to methods to isolate an autologous counterpart of the fibrinogen-containing component in the Tissucol(copyright) system in a practical manner for use in surgery. For example, Siedentop, K. H., et al., Laryngoscope (1985) 95:1074-1076, describes a number of approaches to the precipitation of fibrinogen from plasma in the context of the proposed use of this material as the fibrinogen-furnishing component of a fibrin glue. Four methods were suggested: Precipitation with ethanol, use of unfractionated plasma, cryoprecipitation, and precipitation with ammonium sulfate. The first three methods were considered by the authors to be unsatisfactory; the fourth, which was the method described by Harker, L. A., et al., New Eng J Med (1972) 287:999-1005, was considered to have some promise.
Epstein, G. H., et al., Anals Otol Rhinol and Laryngol (1986) 95:40-45, suggest the use of a fibrinogen preparation from autologous plasma obtained using polyethylene glycol precipitation. These authors adapted the method of Masri, M. A., et al., Thromb Hemeostas (1983) 49:116-119, which involved incubation of the harvested plasma with barium sulfate and magnesium sulfate in order to remove thrombin (and thus prevent premature fibrin formation) followed by treatment of the supernatant from the resulting precipitation with a 30% solution of polyethylene glycol (PEG) of MW approximately 1000. This purified fraction was then mixed with thrombin containing calcium ion in order to form the glue. The isolation process required approximately two-three hours, but the PEG-precipitated fraction could be stored for as much as several weeks, and therefore the preparation could be made in advance of surgery. Autologous fibrinogen preparations obtained following this procedure were shown to be adhesive with implant materials by Feldman, M. C., et al., Arch Otolaryngolxe2x80x94Head and Neck Surg (1988) 114:182-185; additional applications of this approach to other surgical indications were also reported by Feldman, M. C., et al., Arch Opthalmol (1987) 105:963-967; Feldman, M. C., et al., M J Otolog (1988) 9:302-305; Silberstein et al., L. E., et al., Transfusion (1988) 28:319-321.
In addition, the material prepared as described by Epstein et al., by barium sulfate/magnesium sulfate precipitation followed by treatment of the supernatant with polyethylene glycol, was characterized to as to its components by Weisman, R. A., et al., Laryngoscope (1987) 97:1186-1190. The product was found to contain about 13-50 mg/ml of fibrinogen when the material precipitated from 50 ml blood was brought to a volume of 1 ml, wherein this concentration varies with the concentration of PEG. The percent of total protein attributable to fibrinogen ranged from 42-92 percent; the lower the PEG concentration, the higher the percentage of fibrinogen. The concentrations of kallikrein and pre-kallikrein were shown to be reduced to 1-2% of their levels in plasma in the presence of 10% PEG, and Factor XIII activity was shown to be present.
A system for preparing autologous tissue adhesive was also described by Weis-Fogh in PCT Application WO 88/02259 and WO 91/17778, which discloses a reasonably complex system based on ethanol precipitation.
General methods for preparing plasma adhesives have also been described in a series of related U.S. patents by Schwartz et al. assigned to Immuno-AG: U.S. Pat. Nos. 4,414,976; 4,298,598; 4,362,567; and 4,377,572. These methods involve cryoprecipitation of the adhesive material from plasma and various work-up procedures to obtain a mixture of defined composition. In addition, U.S. Pat. No. 4,427,650 to Stroetmann describes a preparation method involving the formation of a cryopreciptiate.
Very early studies on blood fibrinogen, unrelated to the preparation of adhesive compositions, experimented with the use of glycine as a precipitant. A 1963 paper by Kazal, L. A., et al., Proc Sec Exp Biol Med (1963) 10:989-994, described the use of glycine at about 2.2M at room temperature to precipitate fibrinogen after removal of the thrombin with BaSO4/MgSO4 precipitation. Moesson, M. W., et al., Biochemistry (1966) 5:2829-2835, recognized that fibrinogen can be directly precipitated in this manner, but did not assess the suitability of the precipitated material to behave as a controlled adhesive.
None of the foregoing methods is readily adaptable for convenient use of an autologous plasma fraction as an adhesive which can be prepared quickly in the course of the surgical procedure. All of the approaches suggested for preparation of the fibrinogen-containing fraction for this purpose are too time-consuming and complex to be finished in a short enough time period to be accomplished during the course of the surgery. Also, in some procedures, such as cryoprecipitation, special equipment, such as refrigerated centrifuges, is required. While the prior art approach is to prepare the composition in advance, this immediately imposes the necessity for additional procedures for identification and retrieval of the samples matched with the patient, and the concomitant opportunity for error, in addition to the inconvenience to the patient, who must then arrange time for an additional medical appointment. And, of course, this practice is not possible when the surgery is conducted on an emergency basis.
The present invention, by providing a surprisingly simple method and apparatus for the preparation of autologous adhesive, permits the autologous composition to be prepared in the operating room and administered at the time of preparation.
In addition to the problem of preparation, methods to administer the adhesive have not provided sufficient controls to permit clean fusions of tissue to be made. The adhesive is administered as a two-component systemxe2x80x94the fibrinogen preparation as one component and a thrombin/Ca+2 composition as another. The Tissucol(copyright) system uses a double-syringe arrangement wherein the two components are mixed in the injector immediately prior to dispensing. No means to remove debris or excess adhesive from the site of application is provided, and the potential for premature adhesion also exists. The present invention also provides an applicator with a premix immediately upstream of the application outlet means and a means to apply suction at the outlet to maintain the application area in condition for successful adhesion.
The invention provides effective means to prepared and administer autologous plasma-derived adhesive during the course of a surgical procedure. The method of the invention can also be used to prepare the adhesive under less constrained conditions, but the simplicity and ease with which the invention method results in the desired adhesive makes it adaptable to this important use.
The invention process provides the desired adhesive composition in a one-step treatment directly applicable to separated plasma using a recognized, nontoxic precipitant, such as suitable concentrations of amino acids, but preferably a nontoxic polymer such as polyvinyl alcohol (PVA) or polyethylene glycol (PEG). The fraction precipitated by these pharmaceutically acceptable reagents results in a high concentration of fibrinogen in the precipitate, along with other factors necessary for fibrin formation, as well as permitting the use of a simple, disposable apparatus to carry out the manipulations.
Thus, in one aspect, the invention is directed to a process for preparing a fibrinogen adhesive composition from whole blood, which process comprises directly contacting plasma with an amount of polyethylene glycol of molecular weight 200-8000, or other precipitant selected from the group consisting of amino acids and nontoxic hydrophilic polymers, which is effective to precipitate the fibrinogen-containing fraction. Then the precipitated fibrinogen fraction is recovered for use, either by mechanical disruption of the precipitate or pellet or by suspension in an aqueous medium.
In another aspect, the invention is directed to the fibrinogen-containing preparation obtained by the method of the invention.
In still another aspect, the invention is directed to an apparatus for preparing the fibrinogen composition consisting essentially of a device with dual separation chambers with a means for fluid communication between the chambers.
In still another aspect, the invention is directed to an applicator for injecting this or any other two-component system into a human or other animal subject which provides for simultaneous application of suction at the outlet for the components, and to a method to administer the fibrinogen composition using this apparatus.